Circular blades driven by a motor, electric or gas powered, have been used for a number of years for cutting brush and small trees. Such blades are generally mounted on the end of a manually supported arm with the blade rotating in a substantially horizontal plane to cut upright brush and small trees, although the blade can cut in any position. Some prior blades were formed with offset teeth formed in the blade much like a handsaw. Such blades are inefficient and slow cutting.
Circular blades for various purposes have been provided with teeth such as are used in cutting chains for chain saws secured thereto in evenly spaced relation. Blades of this type are shown in U.S. Pats. Nos. 859,554; 1,988,898; 2,992,664; and 3,425,467; Swedish Patent No. 80,528; and French Patent No. 1,194,641. Other blades had lengths of saw chain secured to their periphery, e.g. U.S. Pat. Nos. 2,958,348; 4,563,929; and 4,627,322. A common problem with such blades was their tendency occasionally to "kick back," that is, to give a sudden, forceful and uncontrolled reaction that caused the blade and supporting elements to move suddenly away from the piece being cut. Such "kick backs" have been a source of many injuries. An improved form of such a blade is shown in my co-pending application, Ser. No. 07/124,673, filed Nov. 24, 1987. This blade is characterized by having a plurality of saw chain teeth equally spaced about the periphery of the blade, each of the teeth being formed with a wide ramp or depth gauge preceding the cutting edge. Such blades had much reduced kick back as compared to prior blades and are substantially safer in use. Nonetheless, it is desirable that a brush cutting blade evidence as little kick back force as possible to negate the possibility of an injury producing reaction.